The muscular dystrophies, many caused by mutations in genes encoding proteins of the dystrophin complex, are among the most prevalent and devastating human diseases. No cures exist and current treatments that slow muscle degeneration are largely ineffective. The goal of this application is to apply basic knowledge of several muscular dystrophies to developing therapeutic approaches. In project 1, Jeffrey Chamberlain will isolate alternative types of myogenic stem cells, correct the primary genetic lesion in these cells by gene transfer, and explore the use of such cells for transplantation into syngeneic, dystrophic mice. He will generate myogenic stem cells from dystrophic muscle fibroblasts and explore their ability to generate new muscle tissue in vitro and in vivo and explore the therapeutic use of pericytes isolated from dystrophic muscle. In project 2, Stephen Tapscott will expand the cell therapy approach by examining muscle cell transplantation in the canine model of muscular dystrophy. Enhancement of migration and engraftment of transplanted donor cells will be explored by modulating signaling pathways and extracellular matrix components and genetic manipulations. Finally, specific muscle derived cell populations will be compared for their ability to reconstitute canine skeletal muscle in vivo. In project 3, Stephen Hauschka will modify muscle-specific regulatory cassettes to provide high expression in human muscle cultures. Modified cassettes will then be tested in vivo for expression of therapeutic proteins after AAV and Lentiviral delivery to human muscle xenografts in immunodeficient mice. Clonal satellite cell assays and analysis of human muscle fiber regeneration following xenograft injury will determine whether the satellite cell pool has been stably transduced. In project 4, Stanley Froehner will study a new compensatory gene, NPC1, which markedly reduces the severity of the dystrophic phenotype in mdx mouse muscle. The mechanism of NPC1 phenotype amelioration and its applicability to LGMDs will be studied. Two core facilities will serve the participating laboratories.